DTU researcher behind new design of antennas for hearing aids

A unique model of how radio waves travel around the head as well as ideas for a new design of the antenna in hearing aids is the result of a collaboration between GN Hearing and DTU Electrical Engineering.

By Anne Kirsten Frederiksen

Some of the smallest hearing aids are placed inside the ear canal and are nearly invisible to others. They communicate wirelessly via Bluetooth, both with each other and with for example an iPhone, which allows you to discreetly control the settings of the hearing aids to best fit the acoustics of the surroundings or to plug them directly into the sound from a TV.

The development of miniature hearing aids is, however, not without challenges. One of these is connected to the antenna in the hearing aid.

Antennas are particularly sensitive to the influence of wires and other metal parts which the hearing aid consists of: microphone, speaker, etc. Furthermore, small hearing aids do not come in a standard version—they are 3D-printed to fit the individual user using a cast of the ear canal. This means that the antenna and the other parts are placed differently in each hearing aid which has its very own design.

Radio waves travel around the head

In order to optimize the design of the antennas, it has therefore been important to obtain a deeper understanding of how radio waves to and from the antennas move from ear to ear.

“GN Hearing has been working with DTU on several projects, which has increased our knowledge of how radio waves find their way around the head. This is important knowledge for making the design of the hearing aid and the positioning of the antenna optimal for receiving and emitting signals to the hearing aid in the other ear,” says Søren Kvist, Line Manager at GN Hearing.

It was Industrial PhD Nikolaj Kammersgaard who, on the basis of the preliminary work, designed the final model of how radio waves typically travel around the head.

“It’s been exciting to work on a model which had to work in theory, but also in practice in order to make hearing aids and wireless headphones that use the same technology even better,” says Nikolaj Kammersgaard.

Important for assessing the direction of sounds

Communication between hearing aids is key for the user’s ability to assess where a sound is coming from.

“Generally, hearing aids amplify all sounds. Imagine that you’re waiting for a lift. If the two hearing aids do not communicate with each other, a faint beeping from a lift far to your left will be amplified more than the loud beeping from the lift much closer to you to your right. By communicating with each other, the hearing aids adjust so the sound from the lift at your right is the loudest, and it’s easy for the user to figure out which lift arrives first,” explains Søren Kvist.

Nikolaj Kammersgaard’s model of radio waves has given him insights to subsequently develop a number of new antenna designs which optimize the emission in the direction that the radio waves move.

“We’re looking forward to using these ideas in future versions of our small hearing aids,” says Søren Kvist.

Industrial PhD secures new knowledge

There is no question that GN Hearing wants to continue the collaboration with DTU and new Industrial PhD students.

“We have a large development department, but we’re busy with many projects with sharp deadlines, and we don’t always have the opportunity to immerse ourselves in the individual elements and explore them as thoroughly as Nikolaj has done. But we need this type of knowledge, so we don’t just do what we’ve always done. We must use the new opportunities that technology affords us to constantly improve the hearing aids,” says Søren Kvist.

Like most other young people, Nikolaj Kammersgaard long wondered what to study, when he, after his secondary school leaving examination, had several awards from his participation in the International Mathematical Olympiad.

“I chose to become an electronics and computer engineer because it’s a broad degree which provides the most options for later employment. You can of course work with classic electronics but also in areas as different as space travel, robotics, or health technology. I knew I wanted to create something tangible for the benefit of other people. Hearing aids were therefore an obvious choice,” says Nikolaj Kammersgaard who, after finishing his PhD, was offered a job at GN Hearing.